Abstract Drunk driving is a major public health problem. The National Highway Traffic Safety Administration reported nearly 10,000 people died in alcohol-related crashes in the U.S. in 2014. The problem is further magnified when one considers that each year over 1.3 million drivers in the U.S. are arrested for alcohol-impaired driving. As alarming as these statistics are they pale by comparison to estimates indicating that they only represent 1% of the 121 million self-reported episodes of alcohol-impaired driving among U.S. drivers each year. The proposed research will attempt to curb these alarming trends and move the field forward by conducting a randomized controlled trial testing a brief parent- intervention's ability to change adolescents' drinking, impaired driving, and riding with impaired driver behaviors. Our prior brief parent-based interventions have provided sufficient preliminary evidence of participation, communication, and efficacy for changing under-age drinking to warrant a large-scale comprehensive study. The study will use an extremely rigorous design that meets the Society for Prevention Research Criteria for Efficacy as described in Flay et al.12, a nationally representative sample assessed at 3- waves (baseline, 6 mo. and 12 mo.) to examine generalizability and sustained effects, and an oversampled Hispanic/Latino subgroup to examine the parent-intervention's potential to reduce a health disparity in an underserved population. The aims are as follows: Aim 1: Evaluate the efficacy of the parent intervention (short and long term); Aim 2: Examine mediators of the PBI that directly influence drinking, impaired driving, and riding with impaired driver behaviors; and Aim 3: Identify moderators to help inform future tailoring and improvement in intervention effectiveness. To the extent that the research is successful, it will provide an easy to implement and low cost alternative that can be widely disseminated to address this important public health problem.